There are many kinds of plastic bags, but plastic products that can be directly touched or held on food, especially plastic bags, are only made of polyethylene and polypropylene. These two kinds of plastics can't add additives when making food packaging bags, so they are basically non-toxic. They are allowed to use by the state, but they are more expensive.
In general, the plastic used in non-contact food is made of polyvinyl chloride and other raw materials. Polyvinyl chloride is cheap, easy to colour, bright color, not easy to deform, easy to process and manufacture, can add a variety of additives. This plastic has a wide range of uses, such as industrial and agricultural plastics, household goods and raincoats, sandals, toys and so on.
Polyvinyl chloride (PVC) is the most efficient plastics in China. There are two sources of toxicity of polyvinyl chloride. It is the quality of vinyl chloride plastics. Complete polyvinyl chloride polymerization is a high molecular compound, which can not be absorbed by human and animals. It is basically non-toxic. Its toxicity depends on the toxicity and carcinogenicity of free vinyl chloride monomers, and the polymerization has not been completed. Second, the toxicity of additives added in the process of polymerization, many industrial additives are toxic.
The wholesale additive of plastic bags can dissolve polyvinyl chloride plastics at high temperature. It was widely used in tableware in the 1960s. Steaming rice with this plastic bowl and acute poisoning incidents occurred many times, so it has been forbidden to be used in food packaging materials since the 1970s. After the 1980s, the progress of production technology led to a sharp decline in vinyl chloride monomers, and polyvinyl chloride plastics were once again used as food packaging materials. However, polyvinyl chloride can be used in food packaging and general polyvinyl chloride is different. It has strict standards, non-toxic and harmless raw materials, formulations, additives, assistants, etc. It also strictly restricts the use of restrictions. If it can be used in washers and bottle caps of drinking water pipes, but it does not allow direct contact with food, it can not have more colors.
In the production of many stabilizers and plasticizers, polyvinyl chloride (PVC) needs to be added, and these additives will dissolve when exposed to food containing grease for a long time, especially when the temperature is high in summer, and vinyl chloride will also dissolve into food.
Polyvinyl chloride plastics generally do not cause acute toxicity, its toxicity is mainly chronic toxicity and carcinogenicity. The chronic toxicity of polyvinyl chloride is hepatotoxicity, brain degeneration, interstitial pneumonia and nephropathy. It can also cause hepatic hemangioma and cancer.